World Diabetes Day falls on Saturday, November 14, 2026, and the World Health Organization’s 2026 theme is “Early action on diabetes.” That theme fits type 2 diabetes well: it usually develops gradually and may cause few or no noticeable symptoms, and WHO notes that more than 40% of people living with diabetes are undiagnosed. This guide explains the early signs, the blood sugar numbers used to diagnose type 2 diabetes, and the targets most adults aim for after diagnosis, in both mg/dL and mmol/L. It is part of our Health guides and is meant for education, not self-diagnosis.
Key takeaways
- Type 2 diabetes often develops slowly and can cause no symptoms for years, so testing matters more than waiting for warning signs.
- Common early signs include increased thirst, frequent urination, fatigue, blurred vision, slow-healing sores, and tingling in the hands or feet.
- Diabetes is diagnosed when fasting plasma glucose is 126 mg/dL (7.0 mmol/L) or higher, HbA1c is 6.5% (48 mmol/mol) or higher, or a 2-hour glucose tolerance test reaches 200 mg/dL (11.1 mmol/L) or higher, confirmed by a repeat test unless symptoms are clear.
- For many adults with diabetes, American Diabetes Association (ADA) targets are HbA1c below 7% (53 mmol/mol), 80–130 mg/dL (4.4–7.2 mmol/L) before meals, and under 180 mg/dL (10.0 mmol/L) one to two hours after a meal. Your own targets may differ.
- To convert mg/dL to mmol/L, divide by 18. To convert mmol/L to mg/dL, multiply by 18.
What is type 2 diabetes?
Type 2 diabetes is a long-term condition in which the body doesn’t respond well to insulin (insulin resistance) and, over time, may not make enough of it. Insulin moves sugar (glucose) from the blood into cells for energy. When it falls short, glucose builds up in the blood. Over years, high blood sugar can damage the eyes, kidneys, nerves, heart, and blood vessels, which is why finding it early makes a real difference.
Type 2 is the most common form of diabetes and usually appears in adulthood, though it is increasingly diagnosed in younger people. Type 1 diabetes, by contrast, often develops quickly.
Early signs of type 2 diabetes
- Increased thirst and frequent urination. Extra glucose pulls water into the urine, so you urinate more, including at night, and feel thirsty.
- Constant tiredness. Cells that can’t use glucose properly leave you drained even after rest.
- Blurred vision. High blood sugar can change the shape of the lens in the eye and temporarily blur focus.
- Increased hunger. Cells that aren’t getting enough glucose can trigger hunger even after you eat.
- Slow-healing cuts and frequent infections. Repeated skin, gum, bladder, or yeast infections can point to high blood sugar.
- Tingling, numbness, or burning in the hands or feet. This can signal nerve damage from long-standing high glucose.
- Dark, velvety skin patches in the neck, armpits, or groin (acanthosis nigricans), a visible marker of insulin resistance.
- Unexplained weight loss. This is less common in early type 2 diabetes but can happen.
Many people with type 2 diabetes have none of these signs, so don’t rely on symptoms alone. A blood test is the only reliable way to know.
Who should get tested?
ADA guidance recommends testing all adults starting at age 35, and earlier for adults who are overweight and have other risk factors. For people of Asian descent, ADA uses a lower body mass index (BMI) trigger of 23, because risk rises at lower body weights.
Common risk factors include:
- Overweight or obesity, especially extra weight around the waist
- A parent or sibling with diabetes
- Little physical activity
- Prediabetes, or diabetes during a past pregnancy
- Polycystic ovary syndrome (see our women’s health guides)
- High blood pressure or abnormal cholesterol and triglycerides
- South Asian, Black, Hispanic, Native American, or Pacific Islander ancestry
Blood sugar levels used to diagnose diabetes
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Fasting plasma glucose (no food for 8+ hours) | Below 100 mg/dL (5.6 mmol/L) | 100–125 mg/dL (5.6–6.9 mmol/L) | 126 mg/dL (7.0 mmol/L) or higher |
| 2-hour oral glucose tolerance test (75 g glucose) | Below 140 mg/dL (7.8 mmol/L) | 140–199 mg/dL (7.8–11.0 mmol/L) | 200 mg/dL (11.1 mmol/L) or higher |
| HbA1c (average over about 3 months) | Below 5.7% (39 mmol/mol) | 5.7–6.4% (39–46 mmol/mol) | 6.5% (48 mmol/mol) or higher |
| Random plasma glucose with classic symptoms | Not used | Not used | 200 mg/dL (11.1 mmol/L) or higher |
Things to know about these numbers:
- The ranges above follow ADA criteria. WHO uses 110–125 mg/dL (6.1–6.9 mmol/L) for impaired fasting glucose, so a fasting result of 100–109 mg/dL (5.6–6.0 mmol/L) counts as prediabetes under ADA but not under WHO.
- Diagnosis normally needs two abnormal results, from the same sample or from repeat testing, unless there are clear symptoms with a very high reading.
- HbA1c can be unreliable in anemia, certain hemoglobin variants, and pregnancy, so your doctor may rely on glucose tests instead.
Blood sugar targets after diagnosis
| Measure | Typical target for many non-pregnant adults |
|---|---|
| HbA1c | Below 7% (53 mmol/mol) |
| Before meals (preprandial) | 80–130 mg/dL (4.4–7.2 mmol/L) |
| 1–2 hours after the start of a meal (peak) | Below 180 mg/dL (10.0 mmol/L) |
| Time in range on a continuous glucose monitor (CGM) | 70–180 mg/dL (3.9–10.0 mmol/L), for more than 70% of the day |
| Low blood sugar (hypoglycemia) | Below 70 mg/dL (3.9 mmol/L) |
These are starting points, not personal prescriptions. Your doctor will adjust them for your age, other health conditions, risk of low blood sugar, and pregnancy. A looser HbA1c goal, such as below 8%, can be safer for some older adults or people who are prone to lows, while a tighter goal may suit others. National guidelines in other countries, such as the UK, report in mmol/L and differ slightly. The ADA’s 2026 Standards of Care also place more weight on CGM data alongside HbA1c.
How to convert mg/dL to mmol/L
The United States, India, and many other countries report blood glucose in mg/dL, while the UK, Canada, Australia, and much of Europe use mmol/L. The conversion is the same everywhere:
- mg/dL ÷ 18 = mmol/L (for example, 126 ÷ 18 = 7.0)
- mmol/L × 18 = mg/dL (for example, 7.0 × 18 = 126)
| mg/dL | mmol/L | What it usually means |
|---|---|---|
| 54 | 3.0 | Clinically significant low blood sugar |
| 70 | 3.9 | Low-glucose threshold |
| 100 | 5.6 | Upper limit of normal fasting glucose (ADA) |
| 126 | 7.0 | Diabetes threshold for fasting glucose |
| 140 | 7.8 | Upper limit of normal 2 hours after glucose load |
| 180 | 10.0 | Common after-meal ceiling for adults with diabetes |
| 200 | 11.1 | Diabetes threshold for 2-hour test or symptomatic random test |
| 250 | 13.9 | High; follow your care plan or call your clinician |
Home meters and lab tests are not the same
Home glucose meters and CGMs are designed for day-to-day monitoring, and their readings can differ from a laboratory result. A fingerstick on its own isn’t used to diagnose diabetes. If a home reading is high, book a laboratory test and bring your readings to the appointment.
When to see a doctor
See a doctor if you notice the early signs above, or if you are 35 or older, or younger with risk factors, and have never been tested.
Seek emergency care for very high blood sugar together with vomiting, stomach pain, fruity-smelling breath, fast breathing, confusion, or extreme drowsiness. If you already have diabetes and have low blood sugar (below 70 mg/dL, or 3.9 mmol/L) with shakiness, sweating, or confusion, follow your care team’s plan and get urgent help if it is severe or doesn’t improve.
Can you prevent or delay type 2 diabetes?
For many people with prediabetes, yes. In the large U.S. Diabetes Prevention Program trial, lifestyle changes, mainly modest weight loss and about 150 minutes of physical activity a week, reduced the risk of developing type 2 diabetes by 58%. Practical steps include:
- Aim for about 150 minutes of moderate activity a week, such as brisk walking (browse our fitness guides)
- Build meals around vegetables, legumes, whole grains, and lean protein, and cut back on sugary drinks and refined carbohydrates (see lifestyle tips)
- Aim to lose 5–7% of body weight if you are overweight
- Sleep 7–9 hours, avoid tobacco, and keep up with regular checkups